This invention relates to aircraft fuel systems.
More particularly, the present invention relates to external auxiliary fuel tanks.
In a further and more specific aspect, the instant invention concerns crashworthy fuel tanks.
Auxiliary fuel tanks have been used on aircraft for many years. Internal auxiliary fuel tanks have been developed to be safe and effective, employing crashworthy bladders. In other words, in a survivable crash for the occupants, the tank typically will not rupture and will not contribute to a post-crash fire that may injure or kill the occupants. External auxiliary fuel tanks are conventionally, simply fuel tight containers meeting the requirements of being aerodynamic in shape and securely attachable to the aircraft. Traditionally, crashworthiness has not been a significant consideration since external auxiliary fuel tanks are intended to be dropped or jettisoned before a dangerous situation, such as combat or impending crash.
In the situation of an impending crash of a low flying aircraft, particularly a helicopter, there is often insufficient time to jettison an external fuel tank. If a tank is jettisoned from low altitude, it may often impact close to the crash site. If the tank ruptures, the fuel may contribute to a post crash fire that may injure or kill the occupants. Needless to say, this occurrence is undesirable, as the survivability of the crash will be greatly reduced.
In the situation of combat or the possibility of being struck by bullets from common small arms or man-portable weapons (xe2x80x9csmall armsxe2x80x9d) fire, conventional external auxiliary fuel tanks will rupture and leak fuel. To avoid this situation, the tank is dropped prior to the occurrence or the risk of leakage is accepted.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide a new and improved external auxiliary fuel tank.
Another object of the invention is to provide a crashworthy external auxiliary fuel tank.
And another object of the invention is to provide an external auxiliary fuel tank that will be self-sealing upon the impact of small arms fire.
Briefly, to achieve the desired objects of the instant invention in accordance with a preferred embodiment thereof, provided is an external auxiliary fuel tank for aircraft. The tank includes an elongated shell having a forward shell portion, a rearward shell portion, and an upper side. The forward shell portion and the rearward shell portion are joined by a center structure. The center structure, being generally tubular in shape, defining a central opening and having a longitudinal gap formed opposite an upper side thereof, joins the forward shell portion to the rearward shell portion at a midpoint. A crashworthy bladder having a first end, a second end, and an upper side, is carried within the shell and extends between the forward shell portion and the rearward shell portion through the central opening of the center structure with the upper side of the bladder adjacent the upper side of the shell. A mounting assembly is carried by an upper side of the center structure for attaching the fuel tank to an aircraft.